How the Nervo-Scope and Similar Heat-Detection Devices
Are
Used
to Sell
Unnecessary Chiropractic Treatment

Stephen Barrett, M.D.

Heat-detection has played a significant role in chiropractic's search
for its elusive "subluxation." A 1990 chiropractic monograph on
thermography states that D.D. Palmer used the back of his hand to locate
"hot boxes" along the spinal column in an effort to detect differences
in surface temperature from one side to the other. The authors observed
that "this technique, although subjective and unreliable owing to the
variable sensitivity of the diagnosing physician, has been taught to chiropractic
students since the birth of the profession." [1]

Chiropractic's developer B.J. Palmer became enamored with the "neurocalometer,"
a device invented in 1924 by Dossa D. Evans, D.C..and developed by Otto
Schiernbeck, a consulting engineer on the staff of Palmer College of Chiropractic
[2]. The device had two heat-detecting probes (thermocouples) connected
to a meter that registered whether points on either side of the spine had
different temperatures. In a 1961 book, he stated:

The Neurocalometer was invented and has been developed on the postulate
that a subluxated vertebrae causes pressures on a nerve or group of nerves
as they pass through or emit from spinal column. The instrument has taken
that principle out of the field of theory and placed it strictly in the
realm of science. In other words, it has furnished proof the principle
is correct.

The instrument not only shows when pressure is present, but whether
it has been completely or partially eliminated as a result of the Chiropractic
adjustment of the causative vertebra. When a vertebra is subluxated, it
causes pressure on the surrounding tissues of a nerve or a bundle of nerves
and this causes resistance to flow of nerve energy. This resistance in
turn causes heat at that point, as heat is produced when resistance is
added in a circuit carrying electricity. Neurocalometer is so sensitive
and so constructed with thermocouple detectors and galvanometer that it
registers heat and records it as so many points, or units, on the dial.
It makes comparative heat readings of the spinal area [2].

In the original version, a long cord connected the hand-held thermocouple
portion to a meter housed in a walnut box. In later models, the meter was
housed in the hand-held device. B.J. espoused (and insisted upon leasing)
the device so vigorously that many of his supporters became alienated [3].

Original Neurocalometer

Later Version of Neurocalometer

Nervo-Scope

In the late 1950s, researchers from the Stanford Research Institute surveyed
chiropractors in California and concluded that about 12% used a neurocalometer
and that it was commonly referred to as a "nerve meter." The researchers
also tested the instrument and found that the readings were greatly influenced
by how hard the thermocouples were pressed against the skin [4].

The Nervo-Scope, a neurocalometer descendant, contains a battery, a meter,
and thermocouples at the end of its twin probes. Its findings can be recorded
by connecting the device to a strip-chart recorder. During the 1970s, one
supplier's catalog said that the device was "taking its place alongside
the x-ray in importance" [5]. However, a chiropractic monograph stated
that "unreliability and lack of scientific documentation" have
prevented widespread use of heat detectors in chiropractic practice [1].
A 1993 Canadian chiropractic consensus conference concluded that paraspinal
measurement with thermocouple devices "has not been shown to have good
discriminability, and both their validity and reliability of measurement
are highly doubtful." [6] This is a politically correct way of saying
that the devices are clinically worthless.

Current Use

Despite their questionable value, these thermocouple devices remain popular
among subluxation-based chiropractors and several models are still marketed
[7,8]. Electronics Developments
Lab (EDL), of Danville, Virginia, which currently charges $590 for its
ETS-6 model with carrying case, states:

Nervo-Scope is used and respected for its EFFECTIVE Spinal Analysis,
by the Leading and Successful CLINICS, COLLEGES, SEMINARS, and Thousands
of CHIROPRACTORS . . . Since 1943. . . .

Nervo-Scope will quickly pay for itself in under One year. If you use
Nervo-Scope on ONLY 8 patients per day . . . your Cost per Patient, for
TOTAL PAY BACK, is only 25 Cents Per Patient for One Year, is the Benefits,
which you receive from SATISFIED PATIENTS and CONTINUAL REFERRALS. . .
.

Nervo-Scope is an AUTOMATIC PRACTICE-BUILDER [8].

EDL also markets the ANALAGRAPH, a box-shaped strip-chart recorder that
prints out a continuous recording that resembles the strip of an electrocardiogram.
When its 15-foot cable is plugged into the Model ETS-7 Nervo-Scope, the
device "monitors temperature differentials as small as 0.032ºF."
[8] The two instruments purchased together cost $2,225. EDL's current flyer
states:

Accurate Spinal Analysis requires you to make decisions. With the ANALAGRAPH
you can take the guess work out. Now you will be able to compare Pre-check
readings against your Post-check readings. Now, you can accurately determine
Patterns, and see when Check-out has occurred [sic]. ANALAGRAPH makes it
Easy to see Subluxations that might otherwise have been totally missed
[8].

A widely used chiropractic pediatrics textbook even advises that
Nervoscope devices are useful for examining newborns. The book states:

The method for conducting the exam is dynamic scanning. A bilateral
skin temperature difference is depicted as meter needle movement to one
side or the other. The "reading" . . . is considered significant
if an abrupt "over and back" needle movement is seen over a one
spinal segment distance. The amount of the temperature differential is
thought to be directly proportional to the amount of neurophysiolgic involvement
due to the presence of VSC. The spinal subluxation in the acute stage often
reveals a large variation in temperature. . . . Monitoring the intersegmental
heat differential is one of several parameters of assessing and gauging
patient progress in response to specific spinal adjusting [9].